Outline-measuring is important in product manufacturing to ensure product quality. For example, an image measuring machine is used to capture an image of an object using a charge coupled device (CCD) lens when a lighting device of the image measuring machine is turned on, and transmit the image to an image capturing card of a test computer. Then, the image capturing card displays the image on a display screen of the test computer. The test computer can measure the object by analyzing the image corresponding to the object using an image measurement software installed in the test computer. Image noise (interference noise) can be generated by the lighting device, the CCD lens, and the image capturing card when the image is captured by the CCD lens and the image is transmitted to the image capturing card.
However, the current image measurement software merely analyzes the image noise generated by the lighting device.